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PowerPoint® Lecture Slide Presentation by Patty Bostwick-Taylor, Florence-Darlington Technical College
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
PART A7
The Nervous System
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Functions of the Nervous System
Sensory input—gathering information
To monitor changes occurring inside and outside the body
Changes = stimuli
Integration
To process and interpret sensory input and decide if action is needed
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Functions of the Nervous System
Motor output
A response to integrated stimuli
The response activates muscles or glands
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Functions of the Nervous System
Figure 7.1
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Structural Classification of the Nervous System
Central nervous system (CNS)
Brain
Spinal cord
Peripheral nervous system (PNS)
Nerves outside the brain and spinal cord
Spinal nerves
Cranial nerves
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Functional Classification of the Peripheral Nervous System
Sensory (afferent) division
Nerve fibers that carry information to the central nervous system
Motor (efferent) division
Nerve fibers that carry impulses away from the central nervous system
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Organization of the Nervous System
Figure 7.2
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Functional Classification ofthe Peripheral Nervous System
Motor (efferent) division (continued)
Two subdivisions
Somatic nervous system = voluntary
Autonomic nervous system = involuntary
Sympathetic (‘fight or flight’)
Parasympathetic (normal ‘housekeeping’)
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Nervous Tissue: Support Cells
Support cells in the CNS are grouped together as “neuroglia”
Function: to support, insulate, and protect neurons
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Nervous Tissue: Support Cells
Astrocytes
Abundant, star-shaped cells
Brace neurons
Form connection between capillaries (blood supply) and neurons
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Nervous Tissue: Support Cells
Figure 7.3a
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Nervous Tissue: Support Cells
Microglia
Spiderlike phagocytes
Dispose of debris
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Nervous Tissue: Support Cells
Figure 7.3b
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Nervous Tissue: Support Cells
Ependymal cells
Line cavities of the brain and spinal cord
Circulate cerebrospinal fluid
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Nervous Tissue: Support Cells
Figure 7.3c
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Nervous Tissue: Support Cells
Oligodendrocytes
Wrap around nerve fibers in the central nervous system
Produce myelin sheaths
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Nervous Tissue: Support Cells
Figure 7.3d
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Nervous Tissue: Support Cells
Schwann cells
Form myelin sheath in the peripheral nervous system
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Nervous Tissue: Support Cells
Figure 7.3e
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Nervous Tissue: Neurons
Neurons = nerve cells
Cells specialized to transmit messages
Major regions of neurons
Cell body—nucleus and metabolic center of the cell
Processes—fibers that extend from the cell body
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Nervous Tissue: Neurons
Cell body
Nucleus
Large nucleolus
Processes outside the cell body
Dendrites—conduct impulses toward the cell body
Axons—conduct impulses away from the cell body
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Nervous Tissue: Neurons
Figure 7.4
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Nervous Tissue: Neurons
Axons end in axonal terminals
Axonal terminals contain vesicles with neurotransmitters
Axonal terminals are separated from the next neuron by a gap
Synaptic cleft—gap between adjacent neurons
Synapse—junction between nerves
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Nervous Tissue: Neurons
Myelin sheath—whitish, fatty material covering axons
Schwann cells—produce myelin sheaths in jelly roll–like fashion
Nodes of Ranvier—gaps in myelin sheath along the axon
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Nervous Tissue: Neurons
Figure 7.5
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Functional Classification of Neurons
Sensory (afferent) neurons
Carry impulses from the sensory receptors to the CNS
Cutaneous sense organs
Proprioceptors—detect stretch or tension
Motor (efferent) neurons
Carry impulses from the central nervous system to viscera, muscles, or glands
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Functional Classification of Neurons
Interneurons (association neurons)
Found in neural pathways in the central nervous system
Connect sensory and motor neurons
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Neuron Classification
Figure 7.6
